JPH033147B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to an improvement in a pneumatic defrosting operation method for a multi-layered open case for freezing and refrigeration.

First, with reference to FIG. 1, the structure and cold storage operation of the multi-layer open show case, which is an object of the present invention, will be explained. In the figure, 1 is an outer box of the case body, 2 is an inner box, and 3 is a product display shelf. The case body has a two-layer inner duct 5, an inner and outer layer, which is partitioned by a partition wall 4 between an outer box 1 and an inner box 2, and serves as a circulation ventilation path.
and an outer duct 6 are formed, and an inner fan 7 and an outer fan 8 are installed in each duct, and a cooler 9, which is an evaporator of the refrigerator, is installed in the inner duct.
Further, the ducts 5 and 6 of each layer open upward and downward toward the front opening 10 of the case body, respectively, and form air curtain outlets 11 and 12 and suction ports 13 and 14. Here, the air curtain outlet 11 of the inner duct 5 is lined up on the inside, and the air curtain outlet 12 of the outer duct 6 is lined up and open on the outside.

In the above configuration, during cold storage operation, air is blown into each duct 5, 6 in the direction of the arrow by operating the cooler 9 and each fan 7, 8, and the air is blown into the front opening 10 of the case body between the inside and outside. Air curtains A and B, which are divided into layers and form laminar flows, are formed by blowing from the upper outlet to the lower outlet. Among these, the inner air curtain A is a cold air curtain that is cooled by heat exchange with the cooler 9, and the outer air curtain B that blows out to the outside protects the inner air curtain A. This prevents heat from entering the refrigerator and keeps displayed products cold. Note that the wind speeds of the air curtains A and B are determined so as to obtain optimal air curtain characteristics.

By the way, as is well known, frost adheres to the surface of the cooler 9 as time passes during the cold storage operation described above, and a frosting phenomenon occurs in which frost gradually accumulates. If the cooler becomes covered with frost due to such frost formation,
Not only does this reduce the heat exchange efficiency, but it also narrows the ventilation passages in the duct, making it impossible to ensure the specified circulating air volume, resulting in deterioration of air curtain characteristics, a decrease in cold storage performance, and an increase in the temperature of the air products in the refrigerator. become. For this purpose, the cooler 9 is generally stopped once a certain period of time has elapsed during the cold storage operation, and defrosting is performed to melt and remove the frost adhering to the cooler 9.

As the above-mentioned defrosting methods, heater methods, hot gas methods, and the like are well known, but these methods consume a large amount of power even during defrosting. Therefore, for the purpose of saving power consumption, the defrosting heat source is the in-store air around the case with high enthalpy, and during defrosting, the outside air around the case is actively guided to the inner duct 5 where the cooler 9 is installed, and the outside air is A so-called pneumatic defrosting method has been proposed, in which defrosting is performed by giving the retained heat to the cooler 9, and has come into practical use in some cases.

Next, a conventional defrosting operation method for carrying out the above-mentioned pneumatic defrosting method will be explained with reference to FIG.
That is, when the cooling operation is switched to defrosting, the cooler 9 is stopped and the outer fan 8, which uses a reversible fan motor in advance, is switched to reverse operation. Note that the inner fan 7 continues to operate as in the cold storage operation. Therefore, the ventilation state of each duct is as shown by the dotted line arrows in the figure, after the outside air around the case is sucked in from the air curtain outlet 12 of the outer duct 6, passed through the outer duct 6, and discharged from the air curtain intake port 14. The direction is changed and the air is sucked into the inner duct 5 through the air curtain suction port 13. In addition, the defrosting exhaust gas after exchanging heat with the cooler 9 is discharged from the air curtain outlet 11 as shown by the chain line arrow, flows down the front opening 10 of the case, and forms an air curtain, while a portion It mixes with the outside air and flows back into the inner duct 5, and the rest is dissipated outside the case. In this way, outside air is continuously introduced into the inner duct 5, and pneumatic defrosting is performed in the process of flowing through the cooler 9. The operation chart is shown in Figure 5.

However, in the above-mentioned conventional operating method, since the outside air passes through the outer duct 6 before being introduced into the inner duct 5, there is a large heat loss in the intermediate duct route, and the defrosting efficiency is low. Further, a part of the defrosting exhaust gas is sucked into the inner duct 5 again, so that the defrosting air sent to the cooler 9 becomes a mixture of the defrosting exhaust gas whose temperature has decreased and the outside air around the case.
Therefore, the enthalpy of the defrosting air is lower than that of the outside air surrounding the case, and as a result, in addition to the heat loss, defrosting takes a longer time. Moreover, if the defrosting time takes a long time, the cooler 9 is stopped during this time, so cold storage is not performed, and the influence on the rise in the temperature of the products in the refrigerator becomes greater.

This invention solves the drawbacks of the conventional defrosting operation method described above, suppresses the rise in product temperature, prevents product damage and frost formation due to heat shock, and enables defrosting to be completed in a short time. The purpose of the present invention is to provide a pneumatic defrosting operation method with high defrosting performance.

According to the present invention, the operation of the cooler is stopped during defrosting, the outer fan is switched from normal rotation to reverse rotation throughout the entire defrosting period, and the inner fan is rotated for a predetermined period at the beginning and end of the defrosting period. This is achieved by switching from normal rotation to reverse rotation except for .

The present invention will be described in detail below based on illustrated embodiments.

FIGS. 3 to 5 show ventilation conditions and operation charts at the initial stage and final stage of defrosting, respectively, according to an embodiment of the present invention. Further, according to the present invention, each of the fans 7 and 8 is a reversible fan, and is controlled by a timer so that, for example, 4
When the operation mode is switched from cold storage operation to defrost operation every hour, the cooler 9, that is, the refrigerator, is stopped, and at the same time, the fans 7 and 8 are controlled from normal rotation to reverse rotation according to the operation chart in Fig. 6. Ru.

First, the basic defrosting operation, which is the main part of the defrosting method according to the present invention, will be described with reference to FIG. In the state shown in FIG. 4, both fans 7 and 8 are operated by switching from normal rotation to reverse rotation, contrary to the cold storage operation. Therefore, as shown by the dotted line arrow, the outside air is directly drawn into the inner duct 5 and the outer duct 6 through the air curtain outlets 11 and 12 in parallel, and after flowing through each duct, the air curtain inlet 1
It blows upward from 3 and 14. Moreover, this blown air goes in a direction that opposes gravity, and mixes and disturbs each other, so the air curtain outlet 11, 1
The light does not reach 2 and is emitted from the front to the outside of the case. Therefore, the air curtain outlet 11,
Only the outside air with high enthalpy is continuously sucked in through the cooling device 12, and the amount of defrosting heat given to the cooler 9 is correspondingly large, so that defrosting progresses.

On the other hand, if defrosting is performed using the above defrosting operation method throughout the entire defrosting period, the time required to complete defrosting can be shortened, but on the other hand, during this period, the defrosting exhaust air is Since an air curtain is not formed and a relatively large amount of outside air enters the refrigerator, the temperature inside the refrigerator increases, and
In particular, immediately after switching from cold storage to defrosting, when the product is sufficiently cold, the outside air comes into contact with the product, making it easy for frost and dew to form on the surface of the product, as well as quality deterioration due to heat shock. This can cause a decline in product value.

Therefore, this invention sets a predetermined time difference Δt ₁ and Δt ₂ at the beginning and end of the entire defrosting period, as shown in the operation chart in FIG. 6, and only during this period, as shown in FIG. While operating in the normal direction, only the outer fan 8 is operated in the reverse direction, and defrosting is performed while blowing and forming a defrosting exhaust air curtain at the front opening 10 of the case body in the same manner as in the method shown in Fig. 2. By performing defrosting using the defrosting method shown in FIG.

In this way, by dividing defrosting into three stages, front, middle, and rear, and switching between the defrosting methods shown in Figures 3 and 4 midway through, the defrosting process can be performed immediately after switching from cold preservation operation to defrosting. In the early stages of frost, there is no sudden intrusion of outside air into the refrigerator, making it difficult for heat shock or frost to occur on the products even though the products are sufficiently cold. Thereafter, using the method shown in FIG. 4, outside air is efficiently introduced into the cooler 9 to speed up the progress of defrosting. Furthermore, by switching again to the method shown in Fig. 3 at the end of the period before the end of defrosting, defrosting heat is applied to the cooler 9, and an inner air curtain is blown out by the defrosting exhaust gas whose temperature has decreased, and the next cold storage operation is started. In preparation for this transition, it is possible to prevent a large rise in the temperature inside the refrigerator at the end of defrosting, and the defrosting operation can ideally proceed throughout the entire defrosting period.

By using variable speed motors for the fan motors of each fan 7 and 8, and increasing the speed of the fan motors when the rotation is reversed, it is possible to increase the amount of outside air intake and complete defrosting in a shorter time. .

As described above, according to the present invention, it is possible to complete defrosting more efficiently and in a shorter time than conventional defrosting operation methods, while preventing frost buildup and heat shock on products in the refrigerator. As a result, it is possible to provide a pneumatic defrosting operation method that is highly effective in preventing product temperature increases and product spoilage.

[Brief explanation of drawings]

FIG. 1 is a diagram of the cold storage operation state of an open shower case, FIG. 2 is a diagram of the defrosting operation state according to the conventional defrosting operation method, and FIGS. The defrosting operation state diagrams, FIGS. 5 and 6, which show the ventilation state of frost air, are defrosting operation charts of the conventional and the present invention. 1: Case body outer box, 2: Inner box, 5: Inner duct, 6: Outer duct, 7: Inner fan,
8: Outer fan, 9: Cooler, 10: Front opening.

Claims (1)

[Claims] 1 An inner duct forming a circulation ventilation path and an outer duct surrounding the outer periphery of the inner duct are provided between the outer box and the inner box of the open front case body, and the inner duct accommodates a cooler and an inner fan, and the outer duct accommodates an outer fan. established,
In an open show case where the cooler is operated during cold storage operation and each fan is operated in normal rotation to form multiple layers of cold air curtains inside and outside the front opening of the case body through each duct, the cooler is operated during defrosting. The operation is stopped, and the outer fan is operated by switching from normal rotation during cold storage to reverse rotation throughout the entire defrosting period, and the defrosting period is initialized and
The feature is that the cooler is defrosted by dividing it into three stages: middle and final stages, and switching the inner fan to forward rotation at the beginning of the defrosting period, reverse rotation during the middle period, and forward rotation at the end of the defrosting period. A pneumatic defrosting operation method for an open case.